1. Field of the Invention
The present invention relates to an improvement in a liquid trap device for gas, comprising: a trap housing having a gas inlet and a gas outlet at an upper end; and a liquid filter disposed in the trap housing and provided with a cylindrical filter element whose interior communicates with the gas inlet, the gas outlet being opened in the trap housing but outside the liquid filter so that, when a gas flowing from the gas inlet to the gas outlet passes through the filter element, liquid contained in the gas is trapped by the filter element.
2. Description of the Related Art
An automobile having an engine that uses natural gas as fuel, for example, is equipped with a fuel tank in which compressed natural gas is stored. During the operation of the engine, the high-pressure gaseous fuel introduced out of the fuel tank is decompressed to a predetermined pressure and supplied to the engine. When the natural gas is compressed and stored in the fuel tank, lubricating oil in a compressor used for compressing the natural gas more or less mixes into the fuel to be compressed. Thus, when supplying the gaseous fuel in the fuel tank to the engine, the mixed oil is required to be trapped out of the gaseous fuel. The liquid trap device for gas is used for trapping such mixed liquid out of gas, and is already known as disclosed in Japanese Patent Application Laid-Open No. 7-328364, for example.
In such a conventional type of liquid trap device for gas, an opening provided in an upper end wall of a liquid filter is opened in an upper portion in a filter element, and thus the opening and a gas inlet are comparatively close to each other, leading to a tendency that most of the gas flowing from the opening into the filter element passes through the upper portion of the filter element. As a result, the upper portion of the filter element is brought into a locally saturated state where it is clogged with the trapped liquid, thereby extremely deteriorating a liquid trapping performance in the upper portion of the filter element. Also, when liquid seeps out of the saturated state portion of the filter element, the liquid moves along with the stream of gas that has passed through the filter element, proceeds to the gas outlet, and mixes again into the gas, thereby deteriorating the liquid trapping performance.